Hypothermia can induce reactive oxygen species (ROS) production in cells and tissues (Alva et al.2010). However, the use of deep hypothermia may improve cell protection in clinical situations like ischemia/reperfusion (IR) injury. During the hapatic IR process, an imbalance in the oxidant/antioxidant levels could lead to oxidative stress and the loss of cell viability and liver function. We determine the hepatic oxidant/antioxidant balance and liver damage in a model of isolated rat liver after a normothermic (37 °C) and subnormothermic perfusion at 26 °C and 22 °C. Sprague-Dawley rats were anesthetized with I.P. sodium pentobarbital (50 mg/Kg of body weight) and their livers were removed for perfusion in a non-recirculating system at a flow rate of 4mL/min/g liver. The perfusate used was Krebs-Henseleit buffer (pH 7.4) equilibrated with 95% O2, 5% CO2 (Varietti et al. 2006) and the temperature of the medium was adjusted according to the experimental groups: in normothermia group, livers were perfused during 30 min at 37 °C (N37) and in subnormothermia groups for 15 min at 37 °C followed by 15 min at 26 °C (S26) or 22 °C (S22). The perfusate levels of oxidants and the level of damage indicators were measured at the end of each treatment. As an indicator of liver damage, the alanine aminotransferase (ALT) levels in the perfusate tend to decrease in both subnormothermia (S26 and S22) groups. Nitric oxide values showed a dramatic increase in the perfusate from S22 group and the oxidative damage, measured as malondialdehyde (MDA), was significantly lower in the S22 group when compared to S26 and N37 groups. Liver damage and oxidative stress decreased with the use of subnormothermic perfusion in an isolated rat liver perfusion system with the best protection found in this study to be 22 °C.